Attribution determines which marketing touchpoints receive credit for a conversion. It's essential for understanding ROI and fairly compensating affiliates. Attribution models: - First-touch: First interaction gets 100% credit - Last-touch: Last interaction gets 100% credit - Linear: Equal credit to all touchpoints - Time-decay: Recent touchpoints get more credit - Position-based: First and last get most credit For affiliate programs: - Most use last-click attribution - Cookie windows determine eligibility (7-90 days) - Consider coupon code attribution for influencers